Well, Landau stated that the second film will be like the first one, in that it won't have an ending that will lead up to a sequel. Each movie, he said, would be self-sustaining. So that rules out an "Empire Strikes Back"-type film.

If Pandora were "restored" in the sense that everyone dies except the Na'vi, that'd be sort of an anti-climactic finish... sort of the way the third Matrix film ended (though, that's one of the very few anti-climactic movies that I liked). Cameron isn't an anti-climax writer.

If the RDA strikes back, it'll be hard and fast. That's what she said. The only way I see the Na'vi defeating the RDA is if they combine the use of human technology with all of the clans spread across the moon, along with Eywa's help.

It would become a world war.

The way I see it, there will be situations where the humans will land in uncharted areas that Jake won't know about. We cannot forget that the humans landed in one place. About 90% of the other Na'vi clans on Pandora had absolutely no idea that we were ever here.

The best strategy would be that they land in multiple areas all over the moon, set up bases, and stake out their territory with heavy defense lines, and extreme firepower. All bases would naturally be located away from any "Soul Trees" (areas where flux vortexes are present), so all weaponry would work correctly. If any Na'vi forces tried to attack, they'd be well-protected. If enough were to come to overwhelm a base, they have communications that will alert other nearby bases to come to their aid.

The process of fully defeating the humans will be long and arduous. But it can be done if the Na'vi possess the same technology as the humans, and if Eywa stays prominently involved in the resistance.